The present invention relates to vehicle restraint devices for use adjacent a loading dock. These devices restrict the movement of a truck or transport truck having an IC bar at the rear thereof by engaging or confining the IC bar such that the truck or trailer cannot be withdrawn from the loading dock with the restraint device in its operating position.
A number of prior art structures have been proposed as disclosed in the following patents:
U.S. Pat. No. 4,208,161 PA1 U.S. Pat. No. 4,282,621 PA1 U.S. Pat. No. 4,379,354 PA1 U.S. Pat. No. 4,127,856 PA1 U.S. Pat. No. 4,443,150 PA1 U.S. Pat. No. 4,146,888 PA1 U.S. Pat. No. 4,264,259 PA1 U.S. Pat. No. 4,373,847 PA1 U.S. Pat. No. 4,472,099 PA1 U.S. Pat. No. 4,267,748 PA1 U.S. Pat. No. 4,400,127 PA1 Canadian Pat. No. 1,113,697 PA1 Canadian Pat. No. 1,158,812
Most of these devices are secured to a vertical face of the loading dock by a number of lug bolts which are preferably anchored in concrete. In some cases, this vertical face of the loading dock will be made of concrete block, and in fact will not have any significant strength with respect to a force applied in a direction generally perpendicular to the face of the dock. This obviously causes a problem as the force generated by the truck or trailer being withdrawn from the loading dock and restrained by the device, places a load on these lug bolts which is perpendicular to the face.
The prior art devices use various types of pivotal hooks for engaging the IC bar of the truck or transport trailer. These IC bars are not specifically designed for truck restraint systems and as such can have varying shapes and dimensions, although they are all spaced a given distance below the bed of the trailer or truck. Although it is not mandatory, these IC bars are normally placed closely adjacent the rear of the truck. The varying configuration of the IC bar results in truck restraint systems which will accommodate varying heights and shapes of IC bars and most of these devices include a movable carriage which moves upwardly to strike the IC bar and once so positioned, a hook is adjusted to positively engage the IC bar. Systems of this type have a number of advantages, in that the carriage is moved to ground level when not in use and is not particularly obstructive. In addition, the device is capable of accommodating varying configurations of IC bars and as such has a universal application. The transmission of force to the surrounding structure of the loading dock and the sophistication of the device which involves a movable carriage remains a problem.
Hook attachment of an IC bar can result in the hook being reluctant to disengage the IC bar if a slight shifting of the trailer at the loading dock occurs. Therefore, in some cases, the truck restraint systems which use hooks are prone to problems with respect to release of the vehicle.